Field of the Invention
The present invention relates to removal of electronic components from printed circuit boards. More particularly, the present invention is directed to an improved replaceable tip suitable for use with a solder extractor for removing electronic components from a printed circuit board.
Description of the Prior Art
Repair of electronic equipment often involves the need to remove solder fillets, joints and/or electronic components efficiently without otherwise affecting the circuit as a whole or the other components in the circuit. With respect to solder removal, generally speaking solder extraction is done by applying the front end of a heated tubular element to a soldered area to melt the solder, followed by the application of suction to the tubular member in order to draw off the molten solder through the tube and into a reservoir. U.S. Pat. No. 3,392,897 to Siegel discloses a solder extractor comprising a co-axial instrument of pencil-type construction in which a tubular heated tip, a heat generating element, a molten solder receiving chamber, and a gripping handle are all disposed concentrically and/or in axial succession one to another, with an axial passageway front to rear for the flow of extracted solder. This coaxial pencil-like construction is taught to have a number of advantages in solder removal, namely that this molten solder moves in a straight line, thereby avoiding the possibility of blockage or wear at bend regions and providing a good suction effect from the vacuum source, that the solder extractor as a whole is light and well-balanced, a pencil-like grip permitting close, accurate control of the heated tip with less danger of burn damage to the circuit and components at areas near the solder being removed, that the solder extractor can be readily applied to work pieces that have nearby encumbrances such as upstanding circuit components, and that the radiation and convection heating effects on the work piece are minimized. However, such prior art solder extractors utilize a straight tubular tip, which when utilized in a pencil-like grip, acts to cause molten solder to be drawn substantially parallel to the work piece surface, e.g. the surface of a printed circuit board. This drawing of a solder along the surface of the work piece may be disadvantageous, especially in the case of a circuit board having intricate and/or closely spaced circuits. Alternatively, the tubular tip may be held substantially perpendicular to the circuit board, to desirably draw the molten solder upward and away from the board, but this hand position produces operator fatigue and loss of stability. Moreover, since the tubular tip of the prior art is held in place by a set screw disposed in the solder extractor for this purpose, replacement of the tip, when it becomes worn or fouled with solder can result in the mis-positioning of the tip, causing fluctuations in the length of the projection of the tip from the body of the solder extractor. Such fluctuations can alter heating rates and cause lowered temperatures, if the tip projects too far from the solder extractor, or can cause undesired radiation and convective heating effects on the work piece, due to the solder extractor heating element, when the tip does not project sufficiently from the solder extractor.
In the area of component removal, generally this has been achieved in the past by heating the leads of the component with a heated device to melt the solder at the lead connections to thereby facilitate removal of the component from the board, either by mechanical means, such as with tweezers, or by the use of a blower for blowing the solder from the lead connections, or by use of a vacuum means for attaching the component to the tool.
A yet further way for removing components from a printed circuit board is described in U.S. Pat. No. 4,436,242 which discloses a desoldering device formed with a recess having a box-like configuration which is adapted to closely fit over a leadless component mounted on the circuit board. The box-like recess completely surrounds the component to be removed, and the device operates, not by the use of vacuum, but by molecular attraction of the solder to the component in the recess in order to secure the component within the recess as it is lifted from the board. The component is then removed from the recess by a blast of air through the central passageway extending through the tool.
U.S. Pat. No. 3,382,564 discloses a complex apparatus for soldering and desoldering components on printed circuit boards. Vacuum is utilized for removing the component once the solder has been melted, but desoldering is achieved by a complicated arrangement whereby heated fingers are slidably moved in a vertical direction into and out of contact with the leads of the component.
The prior art component removal devices, such as described above, suffer from the disadvantages that they are cumbersome and expensive. In addition, there are many instances where a repairman of electronic devices must both desolder and solder various connections in the circuitry being repaired, and there is a need to reduce the number of tools required to effect such repairs. For example, a home TV repairman would preferably effect the required repairs with a single tool which can be readily manipulated manually and can be easily adapted using interchangeable components for effecting different functions.